Evaluation of the Survival of Lactobacillus fermentum K73 during the Production of High-Oleic Palm Oil Macroemulsion Powders Using Rotor-Stator Homogenizer and Spray-Drying Technique.

This study aimed to evaluate the survival of the probiotic Lactobacillus fermentum when it is encapsulated in powdered macroemulsions to develop a probiotic product with low water activity. For this purpose, the effect of the rotational speed of the rotor-stator and the spray-drying process was assessed on the microorganism survival and physical properties of probiotic high-oleic palm oil (HOPO) emulsions and powders. Two Box-Behnken experimental designs were carried out: in the first one, for the effect of the macro emulsification process, the numerical factors were the amount of HOPO, the velocity of the rotor-stator, and time, while the factors for the second one, the drying process, were the amount of HOPO, inoculum, and the inlet temperature. It was found that the droplet size (ADS) and polydispersity index (PdI) were influenced by HOPO concentration and time, ζ-potential by HOPO concentration and velocity, and creaming index (CI) by speed and time of homogenization. Additionally, HOPO concentration affected bacterial survival; the viability was between 78-99% after emulsion preparation and 83-107% after seven days. The spray-drying process showed a similar viable cell count before and after the drying process, a reduction between 0.04 and 0.8 Log10 CFUg-1; the moisture varied between 2.4% and 3.7%, values highly acceptable for probiotic products. We concluded that encapsulation of L. fermentum in powdered macroemulsions at the conditions studied is effective in obtaining a functional food from HOPO with optimal physical and probiotic properties according to national legislation (>106 CFU mL-1 or g-1).

Stability and antimicrobial activity of eucalyptus essential oil emulsions.

We evaluated various formulations of oil-in-water emulsions prepared from eucalyptus essential oil, for their stability and antimicrobial activity against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. These formulations were developed using a response surface experimental design and analyzed with Design-Expert® 10 software. The emulsions were prepared in a colloid mill, and emulsion characterization was performed using the zeta ( ζ)-potential, droplet size distribution, and phase separation. The antimicrobial effects were assessed by death kinetics. The droplet size and ζ-potential of the 16 emulsions ranged from 1.071 to 1.865 µm (based on Feret's diameter) and -34.8 to -24 mV, respectively. Three formulations (14, 15, and 16) demonstrated the highest stability parameters (no phase separation) during the 28 days of evaluation. Eucalyptus essential oil emulsions exhibited antimicrobial activity against E. coli, S. aureus, and P. aeruginosa in less than 1 min.

Physical, thermal and thermodynamical study of high oleic palm oil nanoemulsions.

Nanoemulsions are useful for encapsulating nutritionally compounds of the high oleic palm oil (HOPO) including ß-carotene and tocopherols. However, some nanoemulsions can be thermodynamically unstable. For this reason, it is important to understand the thermal and thermodynamic stability of nanoemulsions and to investigate both the parameters that cause, and the mechanisms associated with, the destabilization. In this sense, the DSC, TGA and destabilization analysis were used. In this work, the average droplet size (ADS) and zeta potential (ζ) had a significant influence over HOPO nanoemulsions stability. The range of ADS and ζ were between 162 and 839 nm and -9 to -40 mV, respectively. Furthermore, the HOPO nanoemulsions were establish until temperatures of 80 °C, showing lower loss of weight when the ADS was higher. Additionally, the destabilization of nanoemulsions occurred by the Ostwald ripening mechanism. The Ostwald ripening rate was provided as stability parameter which increased to nanoemulsions with ADS higher between 5 × 10-23 and 8 × 10-23 m3/s.